Ignition device for internal combustion engines

ABSTRACT

An ignition distributor (10) for internal combustion engines having an electronic system for the adjustment of the instant of ignition has a high-voltage distributor (15-18) rotating in synchronism with the engine, the distributor rotor (17) of which is fixable in an infinitely variable manner by an angular amount on a plate (23) of the coupler sheath (20) of the centrifugal adjuster (19). In order to enable ignoring the tolerances of the cooperating parts, the functional position ocf the rotor electrode (18) is adjusted by means of an adjusting ring (31). By means of the centrifugal adjuster (19), the distributor rotor (17) is coordinated with the electronically generated ignition timing and a small diameter of the ignition distributor (10) is thereby made attainable.

STATE OF THE ART

In known ignition devices, the adjustment of ignition timing is attainedvia centrifugal and vacuum devices of the ignition distributor. At thesame time, the distributor rotor is adjusted by the centrifugaladjuster; that is, over the entire engine speed range the rotor has thesame position relative to the cap electrode. The diameter of thehigh-voltage distributor can therefore be relatively small. Furthermore,the rotor electrode and the cap electrodes of the high-voltagedistributor must be dimensioned such that a sparkover of the ignitionspark occurs reliably at all the prespecified ignition adjustmentangles, yet at the same time a sparkover to an incorrect electrode (anincorrect cylinder) is precluded.

In fully electronic ignition timing adjustment, this is accomplishedelectronically, and the ignition triggering means must therefore beseparate from the centrifugal adjuster. As a result of this necessaryseparation of the centrifugal adjuster from the triggering means,however, it is attained that the follow-up is no longer effective; thisnecessitates an increase in the diameter of the high-voltagedistributor. A high-voltage distributor of larger diameter causesproblems, however, because the necessary access to the individualassemblies in the engine area is already problematical, given theusually cramped conditions there.

ADVANTAGES OF THE INVENTION

The problem discussed in the above section is solved with the ignitiondevice for internal combustion engines according to the invention. Theconcept on which the invention is based is the coordinated adjustment ofthe distributor rotor in accordance with the electronically generatedignition timing.

Advantageous further developments of the invention are described in thedependent claims. With the further features of the ignition device of aplate secured to a coupler sheath, and an adjustable connection betweenrotor and plate an adjustment of the distributor rotor is possible. Ifthe device a ring with members which engage the housing and the outerrotor electrode and in particular with claim 6, then as a result all thetolerances of the cooperating parts, except for the adjusting tolerance,can be ignored. As a result, greater high-voltage strength is attainedin the high-voltage distributor.

DRAWING

One exemplary embodiment of the invention is shown in the drawing andexplained in detail in the description below. Shown in actual size are:

FIG. 1, is a cutaway view, a vertical section taken through an ignitiondistributor;

FIG. 2, a top plan view on an adjusting ring and a distributor rotor;and

FIG. 3, in an enlarged detail view, a radial section taken along theline III--III of FIG. 2.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

As part of an ignition device for internal combustion engines having anelectronic system for adjusting the instant of ignition, FIG. 1 shows anignition distributor 10 having a cup-shaped housing 11 secured on theengine block (not shown) and a cap 12 of insulating material. Supportedin the housing 11 are a drive shaft 13 and an inductive transducer 14,which generates pulses and supplies them for processing to a networkdevice (not shown). Molded in the cap 12 are fixed electrodes 15,corresponding in number to the number of engine cylinders, and a middleelectrode 16.

A distributor rotor 17 supplies the high voltage of the middle electrode16 via a rotor electrode 18 to the individual fixed electrodes 15 and tothe spark plugs, not shown, connected therewith.

A centrifugal adjuster 19 is connected to the drive shaft 13 and coupledvia a pair of springs 21 with a coupler sheath 20 supported on the endsegment 22 of the drive shaft 13. A plate 23 having three internalthreads 24 (only one of which is shown) is connected in an undetachablemanner with the coupler sheath 20 by caulking.

The distributor rotor 17 has a plurality of protrusions 25 supported onthe plate 23 and a plurality of flange segments 26, each having a moldedsleeve 27. Each sleeve has an oblong slot 28, through which the threadedshank 29 of a cap screw 30 can be inserted, so that this cap screw canbe threaded into and out of the internal thread 24 of the plate 23. Thelongitudinal extension of the oblong slot 28 is such that when the capscrew 30 is loosened, the distributor rotor 17 can be adjusted byseveral angular degrees relative to the drive shaft 13 and coaxiallythereto in an infinitely variable manner, and the angular positionestablished thereby can be fixed by means of the cap screw 30.

A sleevelike adjusting ring 31 of metal which can be placed, in lieu ofcap 12, to adjust the rotor has on one end segment an internal groove 32and a projection 33, which is secured by means of a sink screw 35'. Thescrew is offset from the adjusting ring 31 in the axial direction. Theoppositely disposed portion of the adjusting ring 31 has a plate likerecess 36, in which a protrusion 34, which points radially inward, issecured by means of a sink screw 35.

The adjusting ring 31 serves to adjust the rotor electrode 18 and tothis end is seated on the rim 37 of the housing 11 in such a manner thatthe projection 33 engages a groove 38 of the rim 37. Subsequently thedrive shaft 13 is brought into the triggering position(instant-of-ignition position) and the distributor rotor 17, releasedfrom the plate 23, is rotated until such time as its rotor electrode 18comes to rest at the plate like protrusion 34. This functional positionis fixed by means of the screw 30. As a result of this adjustment, noneof the tolerances of the cooperating elements need to be taken intoconsideration.

We claim:
 1. An ignition device, for internal combustion engineshavingan electronic system for the adjustment of both the ignitioninstant and the triggering of the ignition instant, and having ahigh-voltage distributor (10) rotating in synchrony with the internalcombustion engine by means of a drive shaft (13), the high-voltagedistributor (10) having a distributor rotor (17) with a rotor electrode(18) which supplies the ignition voltage via a respective fixedelectrode (15) to at least one spark plug, and a cup-shaped housing (11)secured on the engine block, having a rim (37), and receiving the driveshaft,characterized by a centrifugal adjustor (19), the distributorrotor (17) and the drive shaft (13) being coupled via the centrifugaladjuster, which effects a follow-up adjustment of the distributor rotorwith respect to the drive shaft (13), independently of the ignitiontriggering; an adjusting ring (31) determining the relative angularposition of said rotor (17) and said centrifugal adjuster (19), saidring being mountable on the rim (37) of the housing (11) in only onedefined position (38) and having a protrusion (34) pointing into theinterior of the housing (11), which protrusion serves as a stop for theadjustment of the rotor electrode (18); and means (20, 23, 27, 28, 29,30) for clamping the rotor (17) to the centrifugal adjustor (19) in aninfinitely variable manner within an angular range.
 2. An ignitiondevice, as defined by claim 1, wherein the rim (37) of the housing (11)is formed with a groove (38),the adjusting ring (31) has a projection(33) engaging the groove (38), and the protrusion (34) on said ring (31)is angularly offset from the projection (33) by an angle such that, inthe ignition-triggering position of the drive shaft (13), the rotorelectrode (18) assumes its functional position by means of resting onthe protrusion (34).
 3. An ignition device as defined by claim 1,wherein the means for clamping the rotor (17) to the centrifugaladjustor (19) comprisesa plate (23) coupled to the adjustor (19) and aninfinitely variable positioning clamp (28, 29, 30) connecting the rotorto the plate (23).
 4. A device as defined by claim 1 having a couplersheath 20 of the centrifugal adjuster supported rotatably on the driveshaft (13), characterized in that the coupler sheath (20) has a plate(23), on which the distributor rotor (17) is secured.
 5. A device asdefined by claim 4, characterized in that the plate (23) is connected inan undetachable manner to the coupler sheath (20), and that the securingof the distributor rotor (17) on the plate (23) is effected in aninfinitely variable manner within an angular range.
 6. A device asdefined by claim 5, characterized in that the adjustable securing of thedistributor rotor (17) on the plate (23) is effected by means of atleast one screws (30) and that a threaded shank (29) of each screw (30)can be passed through an oblong slot (28) of a sleeve (27) inserted inthe distributor rotor (17) and cooperates with an internal thread (24)of the plate (23).